Inertia-operated switch



April 1, 1969 -rs 3,436,499

INERIIA-OPERATED SWITCH Filed Dec. 21, 1967 j INVENTOR.

BY ame/a 45212 35 KWXM/ 4 7' TORNEY United States Patent US. Cl.200-61.48 1 Claim ABSTRACT OF THE DISCLOSURE An electrical switch havinga pair of spring biased normally open contacts maintained closed by aretaining arm member, rotatable about a pivot point, which is operable,upon the movement of an inertia weight, to open the contacts. A pawllocated on one end of the retaining arm member is engaged by a triggerpin secured to the member which supports the inertia weight to maintainthe retaining arm member in the position to close the switch contacts.Movement of the inertia weight will revolve the trigger pin out ofengagement with the pawl, thereby permitting the force of the contactspring bias to rotate the retaining arm member about its pivot point andopen the switch contacts.

This invention relates to electrical switches and, more specifically, toinertia-operated electrical switches.

Inertia-operated switches are well known in the art, however,heretofore, switches of this type have been cumbersome and included manymoving parts.

'It is, therefore, an object of this invention to provide an improvedinertia-operated switch.

It is another object of this invention to provide an improvedinertia-operated switch having a minimum of moving parts.

In accordance with this invention, an inertia-operated switch isprovided wherein the associated spring biased norm-ally open contactsare maintained in electrical contact by a cam surface on one end of apivotally mounted retaining arm member which is locked in the positionto maintain the contacts closed by a trigger pin secured to aresiliently mounted weight support member engaging a pawl on the otherend thereof and are released to open upon the movement of a weightsecured to the weight support member which rotates the trigger pin outof engagement with the pawl.

For a better understanding of the present invention together withadditional objects, advantages and features thereof, reference is madeto the following description and accompanying drawing in which FIGURE 1is a front view of the inertia-operated switch of this invention,

FIGURE 2 is a section of FIGURE 1 taken along line 2-2 and looking inthe direction of the arrows and FIGURE -3 is a section of FIGURE 1 takenalong line 3-3 and looking in the direction of the arrows.

Referring to the figures of the drawing wherein like elements have beengiven like characters of reference in the three figures, theinertia-operated switch of this invention has a stationary electricalcontact and a movable electrical contact 12 which is mounted upon amovable member 14 spring biased in a direction to open the contacts.With movable contact 12 in electrical engagement with stationary contact10, an electrical circuit is established between conventional bindingposts 15 and 16 through movable member 14. Movable member 14 may be madeof an electrically conductive spring material to provide the necessaryspring bias in a direction to open the contacts, as shown in thedrawing, or

any alternate conventional spring biased movable contact arrangement maybe employed.

The mechanism of the switch of this invention may be enclosed within asuitable. box like enclosure having a top cover 18, a bottom cover 19and sides 20.

Re'siliently mounted within the enclosure is a weight support member 22,to which a weight 24 is attached, having two substantially parallelslots 25 and 26 symmetrical with the center line thereof and a triggerpin 28 secured thereto On the center line thereof for movable supportingweight 24.

Rigidly secured to enclosure member 18 are two stationary pins 30 and31, each engaging a respective slot 25 and 26.

A spring member 34 is secured to the enclosure 20 and arranged to actupon trigger pin 28 in a direction which will force weight supportmember 22 in a directio which will locate the same selected end of eachof slots 25 and 26 against the respective one of the stationary pins 30and 31.

Pivotally mounted about pivot point 35 is a retaining arm member 38having a pawl 39 on one end engageable with trigger pin 28 and a camsurface 40 on the other end which engages movable member 14, as isclearly shown in FIGURE 1.

The switch is operated by movement of weight 24. Movement of weight '24to the left, as looking at FIG- URE 1, will produce rotation of weightsupport member 22 in a counterclockwise direction about fixed pin 31 tothe extent permitted by the length of slot 25. Rotation in thisdirection will rotate trigger pin 28 out of engagement with pawl 39which releases retaining arm member 38. With retaining arm member 38thus released, the spring bias force of movable member 14, actingthrough cam surface 40, rotates retaining arm member 38 in acounter-clockwise direction about pivot point 35 and opens contacts 10and 12 to interrupt the electrical circuit between binding posts 15 and16. Movement of weight 24 to the right, as looking at FIGURE 1, willproduce rotation of weight support member 22 in a clockwise directionabout fixed pin 30 to the extent permitted by the length of slot 26 torotate trigger pin 28 out of engagement with pawl 39 which releasesretaining arm member 38. With retaining arm member 38 thus released, thespring bias force of movable member 14, acting through cam surface 40,rotates retaining arm member '38 in a counterclockwise direction aboutpivot point 3 5 and opens contacts 10 and 12 to interrupt the electricalcircuit between binding posts 1'5 and 16. Movement of Weight 24 in adownward direction as viewing FIGURE 1 will also move trigger pin 28 outof engagement with pawl 39 to release retaining arm member 38 and permitthe switch contacts to open in the manner herein explained.

Attached to retaining arm member 38 is a reset rod which extends throughenclosure member 20 and is attached to a reset handle 46. As retainingarm member 38 is revolved in a counter-clockwise direction about pivotpoint 35 by the spring bias force of movable member 12 upon thedisengagement of trigger pin 28 from pawl 39, reset rod 45 is moved tothe right, as looking at FIGURE 1. To reset the switch, reset rod 45 ispushed to the left through reset handle 46 to rotate retaining armmember 38 in a clockwise direction about pivot point 35 by an amountsufficient to re-engage trigger pin 28 with pawl 39 to reset the switchmechanism for the next operation.

While the preferred embodiment of the present invention has been shownand described, it will be obvious to those skilled in the art thatvarious modifications and substitutions may be made without departingfrom the spirit of the invention.

What is claimed is:

1. An inertia-operated switch having a stationary electrical contact anda movable electrical contact mounted upon a movable member spring biasedin a direction to open the electrical contacts comprising, an enclosure,a weight, a weight support member having two substantially parallelslots symmetrical with the center line thereof and a trigger pin securedthereto on the-center line thereof resiliently mounted within saidenclosure for movably supporting said weight which is attached thereto,first and second stationary pins secured to said enclosure and eachengaging a respective said slot, a spring member secured to saidenclosure and. arranged to act upon said trigger pin in a directionwhich will force said weight support member in a direction which willlocate the same selected end of each of said slots against the.respective one of said first and second stationary pins and a retainingarm member mounted for rotation about a pivot point having a pawl on oneend thereof engageable with said trigger pin and a cam surface on theother end thereof in engagement with said movable member upon which saidmovable contact is mounted for operating said movable contact intoelectrical engagement with said stationary contact against the force ofsaid spring bias upon the rotation of said retaining arm member in afirst direction about said pivot point.

References Cited UNITED STATES PATENTS 9 1,591,149 7/ 1926 Waltamath200-615 2,130,706 9/1938 Salmond 200'61.5 2,223,097 11/ 1940 Ehret 20061.5 2,671,832 3/1954 Hansard et al. 200 6 1.5 X 2,879,349 3/1959Thompson 20061.5 2,966,562 12/1960 McElvain ZOO- 61.5 2,986,614 5/ 1961Minch 200 615 FOREIGN PATENTS 968,461 2/1958' Germany.

ROBERT K. SCI-LAEFER, Primary Examiner. ROBERT A. VANDERHYE, AssistantExaminer.

US. Cl. X.R. 20061.49, 61.5

